sql数据库外键问题

Question

我有一项学校作业让我和我的朋友们头疼...所以这是我执行的查询，一次一个...

CREATE DATABASE GamblingSociety;

USE GamblingSociety;

CREATE TABLE GamblingDen
(
    Name VARCHAR (20) PRIMARY KEY,
    Address VARCHAR (50),
    Phone VARCHAR (10)
);

CREATE TABLE Room (
    RoomNr INT,
    GameCapaity INT,
    GamblingDenName VARCHAR (20),
    PRIMARY KEY (RoomNr, GamblingDenName),
    FOREIGN KEY (GamblingDenName) REFERENCES GamblingDen (Name)
);

CREATE TABLE Employee (
    SSN CHAR (11) PRIMARY KEY,
    Name VARCHAR (20),
    Address VARCHAR(50),
    Salary INT,
    isBoss BOOL,
    GamblingDenName VARCHAR (20),
    FOREIGN KEY (GamblingDenName) REFERENCES GamblingDen (Name)
);

CREATE TABLE GameType (
    Name VARCHAR (20) PRIMARY KEY,
    WinningProcentage FLOAT,
    ResponsibleEmployee CHAR (11),
    FOREIGN KEY (ResponsibleEmployee) REFERENCES Employee (SSN)
);

CREATE TABLE Supplier (
    Name VARCHAR (20) PRIMARY KEY,
    Address VARCHAR (50)
);

CREATE TABLE SupplierOfGameType (
    SupplierName VARCHAR (20),
    GameTypeName VARCHAR (20),
    PRIMARY KEY(SupplierName, GameTypeName),
    FOREIGN KEY (SupplierName) REFERENCES Supplier (Name),
    FOREIGN KEY (GameTypeName) REFERENCES GameType (Name)
);

CREATE TABLE GamblingTable (
    TableNr INT,
    RoomNr INT,
    GamblingDenName VARCHAR (20),
    GameTypeName VARCHAR (20),
    Comments VARCHAR (128),
    PRIMARY KEY (RoomNr, TableNr, GamblingDenName, GameTypeName),
    FOREIGN KEY (RoomNr, GamblingDenName) REFERENCES Room (RoomNr, GamblingDenName),
    FOREIGN KEY (GameTypeName) REFERENCES GameType (Name)
);

CREATE TABLE Shylock (
    Phone CHAR (10) PRIMARY KEY,
    Name VARCHAR (20),
    Contry CHAR (3)
);

CREATE TABLE Customer (
    SSN CHAR (11) PRIMARY KEY,
    Name VARCHAR (20),
    Phone CHAR (10),
    Address VARCHAR (50)
);

但是最后一个查询不起作用：

USE GamblingSociety;

CREATE TABLE GamblingInstance (
    StartTime DATETIME,
    EndingTime DATETIME,
    GamblingDenName VARCHAR (20),
    TableNr INT, 
    GameTypeName VARCHAR (20), 
    Customer CHAR (11),
    Shylock CHAR (10), 
    Debt INT, 
    DebtPayed BOOL,
    DebtPayedDate DATETIME,
    PRIMARY KEY (StartTime, GameTypeName, Customer),
    FOREIGN KEY (GamblingDenName, TableNr, GameTypeName) REFERENCES GamblingTable (GamblingDenName, TableNr, GameTypeName),
    FOREIGN KEY (Customer) REFERENCES Customer (SSN),
    FOREIGN KEY (Shylock) REFERENCES Shylock (Phone)
);

它给了我这个错误： “错误代码：1005。无法创建表'gamblingsociety.gamblinginstance'（errno：150）”

如果我将其替换

FOREIGN KEY (GamblingDenName, TableNr, GameTypeName) REFERENCES GamblingTable (GamblingDenName, TableNr, GameTypeName),

为：

FOREIGN KEY (GameTypeName) REFERENCES GamblingTable (GameTypeName),

它可以工作，所以它与GamblingDenName和TableNr有关。

我用谷歌搜索了一下，发现了很多提示，但还没有任何效果……

所以有人有任何想法吗？

提前致谢！

Answer 1

GamblingTable 中没有可以满足此参考的键：

  REFERENCES GamblingTable (GamblingDenName, TableNr, GameTypeName),

也就是说，GamblingTable 中没有 GamblingDenName、TableNr、GameTypeName 为的键唯一的列，或前三列。

有一个满足REFERENCES GamblingTable (GameTypeName)的密钥，这就是该版本有效的原因。

（我不得不说，我从未真正见过外键被用来作为其他外键的父级，但我想它是有效的）。